(i) 206L S/N 45004 through 45049, 40451 through 45153, and 46601 through 46617;

(ii) 206L-1 S/N 45154 through 45790;

(iii) 206L-3 S/N 51001 through 51612;

(iv) 206L-4 S/N 52001 through 52163, 52165 through 522l2, and 52214 through 52216.

(v) 206L-4T ALL S/N.

Effective date: October 7, 1999

Compliance : Required as indicated in TC AD CF-98-42R2

(i) 206L S/N 45004 through 45049, 40451 through 45153, and 46601 through 46617;

(ii) 206L-1 S/N 45154 through 45790;

(iii) 206L-3 S/N 51001 through 51612;

(iv) 206L-4 S/N 52001 through 52163, 52165 through 522l2, and 52214 through 52216.

Compliance is required as indicated, unless already accomplished.

There have been at least seven reports of cracks to the tail boom skin in the area of the horizontal stabilizer. The cracks were found by normal visual inspection. The average time accumulated on the tail booms was more than 2000 hours; however, cracks could develop at any time. A review of crack growth rates after Airworthiness Directive (AD) CF-98-42 was issued indicated a need to detect cracks earlier. This necessitated the use of non destructive inspections of the tail boom skin under the support plates. As an interim measure, these inspections were mandated by CF-9842R1.

This revision mandates Alert Service Bulletin (ASB) 206L-99-115 Revision A, which introduces the reinforcement of the tail boom skin around the left horizontal stabilizer cutout, together with instructions for improved installation of the horizontal stabilizer and its supports. Accomplishment of ASB 206L-99-115 Revision A constitutes terminating action to ASB 206L-98-114 as mandated by CF-98-42R1.

To ensure the early detection of cracks and the structural integrity of the tail boom, accomplish the following:

1. Initially, before the next flight after the effective date of this directive, perform a visual inspection of the tail boom in accordance with BHTC Alert Service Bulletin (ASB) 206L-98-114 dated 25 November l998 or later revisions approved by the Director, Aircraft Certification, Transport Canada.

2. Within 50 hours air time after the effective date of this directive:

(a) Remove the upper and lower supports of the horizontal stabilizer in accordance with the applicable sections of the Maintenance Manual.

(b) In accordance with section 62 of Standard Practices Manual BHT-ALL-SPM, perform a one-time fluorescent penetrant inspection of the tail boom skin in the area at least 3/4 inch around the edges of the horizontal stabilizer openings.

3. Subsequently, before the first flight of each day perform a visual inspection of the tail boom in accordance with the above noted ASB 206L-98-114.

Note: While away from technical support, this visual check may be done by pilots as part of the Preflight Check. To exercise this option, pilots must first be trained by a technician on the requirements of ASB 206L-98-114, Figure l.

4. At every l00 hours air time, plus 10 hours, remove the support plates and visually inspect for cracks the entire edge of the horizontal stabilizer opening on both sides of the tail boom, using a 10X magnifying glass.

5. If a crack is found on the tail boom skin as a result of one of the above inspections, replace the tail boom before the next flight. Report findings to Transport Canada, Continuing Airworthiness Division (AARDG) at facsimile (613) 996-9178 by use of a Service Difficulty Report form, and to Bell Helicopter Textron Canada - Product Support Engineering at facsimile (450) 433-0272.

6. No later than 31 March 2000, modify the tail boom in accordance with Parts I, II and III of BHTC ASB 206L-99-1l5 Revision A, dated 9 June 1999, or later Transport Canada approved revisions. Installation of the doubler terminates all actions required by paragraphs 1 through 5 of this directive.

This revision supersedes Airworthiness Directive CF-98-42R1 issued 16 February 1999.

This directive retains the 31 March 1999 effective date of AD CF-98-42R1.

For Minister of Transport

B. Goyaniuk

Chief, Continuing Airworthiness

For further information contact a Transport Canada Centre, or Mr. Bogdan Gajewski, Continuing

Airworthiness, Ottawa, telephone (613) 952-4450, facsimile (613) 996-9l78 or e-mail gajewsb@tc.gc.ca.